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1. Cyber Attack and Defense for Smart Inverters in a Distribution System

   Sun, C. C. ; Zhu, R. ; Liu, C. C. ( June 2019 , CIGRE Study Committee D2 Colloquium, Helsinki, Finland)

   The fast-growing installation of solar PVs has a significant impact on the operation of distribution systems. Grid-tied solar inverters provide reactive power capability to support the voltage profile in a distribution system. In comparison with traditional inverters, smart inverters have the capability of real time remote control through digital communication interfaces. However, cyberattack has become a major threat with the deployment of Information and Communications Technology (ICT) in a smart grid. The past cyberattack incidents have demonstrated how attackers can sabotage a power grid through digital communication systems. In the worst case, numerous electricity consumers can experience a major and extended power outage. Unfortunately, tracking techniques are not efficient for today’s advanced communication networks. Therefore, a reliable cyber protection system is a necessary defense tool for the power grid. In this paper, a signature-based Intrusion Detection System (IDS) is developed to detect cyber intrusions of a distribution system with a high level penetration of solar energy. To identify cyberattack events, an attack table is constructed based on the Temporal Failure Propagation Graph (TFPG) technique. It includes the information of potential cyberattack patterns in terms of attack types and time sequence of anomaly events. Once the detected anomaly events are matched with any of the predefined attack patterns, it is judged to be a cyberattack. Since the attack patterns are distinguishable from other system failures, it reduces the false positive rate. To study the impact of cyberattacks on solar devices and validate the performance of the proposed IDS, a realistic Cyber-Physical System (CPS) simulation environment available at Virginia Tech (VT) is used to develop an interconnection between the cyber and power system models. The CPS model demonstrates how communication system anomalies can impact the physical system. The results of two example cyberattack test cases are obtained with the IEEE 13 node test feeder system and the power system simulator, DIgSILENT PowerFactory. 

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2. Residual Saturation Based Kalman Filter for Smart Grid State Estimation Under Cyber Attacks

   Rana, Md Masud ; Bo, Rui ; Choi, Bong Jun ( August 2019 , Proceedings of 9th IEEE International Conference on CYBER Technology in Automation, Control and Intelligent Systems (IEEE-CYBER 2019))

   Most of the traditional state estimation algorithms are provided false alarm when there is attack. This paper proposes an attack-resilient algorithm where attack is automatically ignored, and the state estimation process is continuing which acts a grid-eye for monitoring whole power systems. After modeling the smart grid incorporating distributed energy resources, the smart sensors are deployed to gather measurement information where sensors are prone to attacks. Based on the noisy and cyber attack measurement information, the optimal state estimation algorithm is designed. When the attack is happened, the measurement residual error dynamic goes high and it can ignore using proposed saturation function. Moreover, the proposed saturation function is automatically computed in a dynamic way considering residual error and deigned parameters. Combing the aforementioned approaches, the Kalman filter algorithm is modified which is applied to the smart grid state estimation. The simulation results show that the proposed algorithm provides high estimation accuracy. 

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3. Cyber-Attacks and Mitigation in Blockchain Based Transactive Energy Systems

   Barreto, Carlos ; Eghtesad, Taha ; Eisele, Scott ; Laszka, Aron ; Dubey, Abhishek ; Koutsoukos, Xenofon ( July 2020 , 3rd IEEE International Conference on IndustrialCyber-Physical Systems (ICPS 2020))

   Power grids are undergoing major changes due to the rapid adoption of intermittent renewable energy resources and the increased availability of energy storage devices. These trends drive smart-grid operators to envision a future where peer-to-peer energy trading occurs within microgrids, leading to the development of Transactive Energy Systems. Blockchains have garnered significant interest from both academia and industry for their potential application in decentralized TES, in large part due to their high level of resilience. In this paper, we introduce a novel class of attacks against blockchain based TES, which target the gateways that connect market participants to the system. We introduce a general model of blockchain based TES and study multiple threat models and attack strategies. We also demonstrate the impact of these attacks using a testbed based on GridLAB-D and a private Ethereum network. Finally, we study how to mitigate these attack. 

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4. Design and implementation of a multi winding high frequency transformer for MPSST application

   https://doi.org/10.1109/ICRERA.2017.8191108  

   Rashidi, Mohammad ; Bani-Ahmed, Abedalsalam ; Nasiri, Robabeh ; Mazaheri, Azadeh ; Nasiri, Adel ( November 2017 , 2017 IEEE 6th International Conference on Renewable Energy Research and Applications (ICRERA))

   Development of the new generation of high power and high frequency power electronic switches along with the need for compact controllable converters for utilization of distributed energy resources in the grid, have led to significant developments in the area of solid state transformers in the last years. The design process of a high frequency transformer as the main element in the solid state transformer is illustrated in this article. A multi winding transformer for multiport SST application is designed, studied and built in this research. In a MPSST several windings feed the core. As the result, coupling coefficient between each pair of windings, become an important factor which is studied in this study. Since the transformer is designed for high frequency applications, the power loss in the wire and core of the transformer increases as the result of higher skin effect and eddy current loss in high frequency. Three important factors in the design of HF transformer for MPSST are discussed in the paper. First, four different possible core materials are compared based on their flux density, frequency range, loss and price. Then the cable selection is illustrated and finally, different winding placement and distribution on the same core are suggested and the inductance and coupling coefficient matrices are calculated using ANSYS Maxwell 3D simulation. The transformer is built in the lab and the inductance values matches the expected values from the simulation. 

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5. NIST Transactive EnergyModeling and Simulation Challenge Phase II Final Report

   https://doi.org/10.6028  

   Holmberg, David ; Burns, Martin ; Bushby, Steven ; McDermott, Tom ; Tang, Yingying ; Huang, Qiuhua ; Pratt, Annabelle ; Ruth, Mark ; Bichpuriya, Yogesh ; Rajagopal, Narayanan ; et al ( January 2019 , NIST special publication)

   The NIST Transactive Energy (TE) Modeling and Simulation Challenge for the Smart Grid (Challenge) spanned from 2015 to 2018. The TE Challenge was initiated to identify simulation tools and expertise that might be developed or combined in co-simulation platforms to enable the evaluation of transactive energy approaches. Phase I of the Challenge spanned 2015 to 2016, with team efforts that improved understanding of TE concepts, identified relevant simulation tools and co-simulation platforms, and inspired the development of a TE co-simulation abstract component model that paved the way for Phase II. The Phase II effort spanned Spring 2017 through Spring 2018, where the teams collaboratively developed a specific TE problem scenario, a common grid topology, and common reporting metrics to enable direct comparison of results from simulation of each team's TE approach for the defined scenario.This report presents an overview of the TE Challenge, the TE abstract component model, and the common scenario.It also compiles the individual Challenge participants' research reports from Phase II. The common scenario involves a weather event impacting a distribution grid with very high penetration of photovoltaics, leading to voltage regulation challenges that are to be mitigated by TE methods. Four teams worked with this common scenario and different TE models to incentivize distributed resource response to voltage deviations, performing these simulations on different simulation platforms. A fifth team focused on a co-simulation platform that can be used for online TE simulations with existing co-simulation components. The TE Challenge Phase II has advanced co-simulation modeling tools and platforms for TE system performance analysis, developed a referenceable TE scenario that can support ongoing comparative simulations, and demonstrated various TE approaches for managing voltage on a distribution grid with high penetration of photovoltaics. 

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